Hey so I have had this stringer for about 5 months and never had any problems with the tensioner, but lately something has been messed up with the tensioner.

so when the tensioner gripper gets out of place, u have to re ajust it by pulling it around, right? Well, I'll notice that it's building up resistance and getting harder to pull, and then sometimes it will literally get to the point where it will not move, causing me to pull tension with no string until the gripper gets back to where I want it. Sometimes it will magically go back to normal and its great but it will slowly get worse again. I have tried tightening and loosening certain screws, but nothing seems to affect it. I know one time when it was tightening up I was really rough with it kinda forcing it, and it went back to normal for a bit.

any help would be appreciated. I have never cleaned it so I'm thinking that may be the problem, but I'm not really sure what or how to clean it.

Like others have said, it's probably the spring. Check your original packaging... mine came with a spare spring when I bought it. Looks like a keyring... but it's the clutch spring. Hopefully you didn't throw it away.